Some coins struck at the Denver Mint for 2015 Uncirculated Mint sets have what at least one grading service calls “Prooflike” surfaces, with some of these coins selling for premiums at auctions.

The Prooflike surfaces apparently result from environmental conditions at the Denver Mint and the subsequent handling of the coins. Coins struck for the same sets at the Philadelphia Mint are produced under different environmental conditions, resulting in more typical Uncirculated finishes.

Numismatic Guaranty Corp. has graded and encapsulated a number of 2015-D coins with the PL (for “Prooflike”) designation on the grading label. The coins include Lincoln cents, Roosevelt dimes, Kennedy half dollars, and Dwight D. Eisenhower Presidential dollars, according to NGC Vice President Scott Schechter.

The Prooflike designation has not been used thus far for any of the Philadelphia Mint coins in the sets, according to Schechter. The coins certified as “Prooflike” by NGC were extracted from 2015 Uncirculated Mint sets submitted in their original Mint packaging, according to Schechter.

The certified Prooflike Denver Mint strikes coins are garnering premiums on the secondary market, primarily in eBay auctions. One NGC MS-68PL red 2015-D Lincoln cent sold Aug. 30 for $328.33.

Modern U.S. Prooflike coins are typically Uncirculated strikes that exhibit surface characteristics similar to regular mirrored Proof coins. Proof coins are struck under more exacting processes to achieve the Proof finishes.

Collectors Gerald Higgs and David St. Thomas independently noticed the differences in the quality of the Denver Mint strikes compared to the Philadelphia Mint strikes in the 2015 Uncirculated Mint sets each received. St. Thomas’ attention was drawn to the Roosevelt dime while Higgs’ was attracted to the five Presidential and Native American dollar coins in the set.

Higgs wondered how the Denver Mint coins gained the unusual finishes and asked Coin World whether enhanced planchet quality, adjusted striking pressures or modified handling procedures for its collector products was responsible.

U.S. Mint officials provided Coin World the following explanation:

“The Denver and Philadelphia plants have a few factors that contribute to some slight variation in products.

“Denver has a much smaller footprint than Philadelphia. As such, Denver’s facility cannot accommodate a conveyor system and their process is more batch-style, where certain steps are grouped and performed in increments before proceeding forward. Philadelphia has a much larger footprint and a conveyor system that allows them to process in a continuous manner without incremental steps. The difference in size and layout also determines the type of equipment that each plant is capable of operating. These differences necessitate some variation in the plants’ processes.

“Additionally, since one plant [Denver] is located in the arid western plains and the other [Philadelphia] in a marshy area not far from the sea, there are natural causes for the plants’ process variations. Elements such as climate, humidity, and air and water quality can have a drastic effect on the manufacturing processes such as the effectiveness of cleaning compounds or adherence of stamping lubricant.

“The United States Mint is committed across the bureau to producing high quality products for customers and to serve the nation’s need for coinage. The Denver and Philadelphia plants continually strive to improve the manufacturing process.  Each facility is instituting and refining process controls, working to mitigate environmental factors, and sharing knowledge and experience to produce outstanding products for our customers.

“In addition to the statement above, please note that although the plants have factors that contribute to slight variation in products, we work very hard to match the processes and quality of the Denver and Philadelphia Mints. Regardless of inherent differences between any and all of our locations, including San Francisco and West Point, we are committed to producing high quality products. We welcome and highly appreciate direct customer feedback and we will use it to guide our actions and continuously develop our quality system.”

The 2015 Uncirculated Mint set, offered at $28.95, has 14 coins each from the Denver and Philadelphia Mints. Each Mint provides a Lincoln cent; a Jefferson 5-cent coin; a Roosevelt dime; America the Beautiful quarter dollars for the Homestead National Monument of America, Kisatchie National Forest, Blue Ridge Parkway, Bombay Hook National Wildlife Refuge and Saratoga National Historical Park; a Kennedy half dollar; a Native American dollar; and Presidential dollars commemorating Harry S. Truman, Dwight D. Eisenhower, John F. Kennedy, and Lyndon B. Johnson.

Differences have been known

Differences between Denver Mint and Philadelphia Mint coins have been noticed by the collecting community for years.

“The Uncirculated Set coins from the Denver Mint … usually do have a different appearance than their Philadelphia Mint counterparts,” according to Max Spiegel, vice president of sales and marketing for NGC’s parent firm, Certified Collectibles Group.

“On occasion, the Denver Mint coins display Prooflike surfaces and will be designated by NGC as such.”

For the 2015 coins, Spiegel noted, “Of the 2015 Presidential dollars we have observed 23 Dwight Eisenhower pieces from the Denver Mint that merited the PL designation. None of the other 2015 Presidential Dollars that we observed, however, merited the PL designation.”

The NGC Census indicates that as of Nov. 2, in addition to the 23 Prooflike Eisenhower Presidential dollars, the grading service has also certified, in grades from Mint State 66 to MS-68, a total of 52 2015-D cents as red Prooflike; 72 of the 2015-D dimes from MS-66 to MS-68 in Full Torch Prooflike; five additional dimes as MS-67 Full Torch DPL (deep Prooflike); and 48 of the 2015-D half dollars from MS-65 Prooflike to MS-68 Prooflike.

Most of the Prooflike issues offered on eBay are labeled as Early Releases, having been received at NGC within 30 days of the April 24, 2015, sales launch.

As of Nov. 2, one MS-67 Prooflike 2015-D Eisenhower Presidential dollar was being offered with a Buy It Now option at $194.95. EBay’s completed listings for a non-Prooflike NGC MS-67 2015-D Eisenhower Presidential dollar from a set showed no bids for an auction that closed Nov. 4 that had an opening bid of $7.95. A non-Prooflike MS-68 2015-D Eisenhower dollar was being offered with a Buy It Now option at $74.95.

In addition, eBay reports confirmed sales of a number of the Prooflike dimes, including an NGC MS-68 Full Torch Prooflike example that sold Oct. 31 for $76; an NGC MS-67 Full Torch Prooflike example that sold Sept. 25 for $18.81; and another NGC MS-67 Full Torch Prooflike example that sold Sept. 23 for $17.17.

For comparison, completed eBay sales for non-Prooflike NGC-graded dimes from the sets showed an Aug. 8 sale of MS-67 Full Torch 2015-D and 2015-P dimes sold together for $10.27 and a two-piece non-Prooflike MS-68 dime set of Philadelphia and Denver Mint coins for $14.50 on Sept. 9

Confirmed eBay sales of Prooflike 2015-D Kennedy half dollars from the 2015 Uncirculated Mint sets include an NGC MS-67 Prooflike coin that sold Sept. 15 for $32.88; another NGC MS-67 Prooflike piece that sold Sept. 25 for $22.50; and another NGC MS-67 Prooflike half dollar that sold for $17.10 on Sept. 20.

Completed sales of non-Prooflike NGC-graded Kennedy half dollars offered as two-piece sets of 2015-D and 2015-P coins include an Aug. 8 sale of NGC MS-67 coins for $20.45; another two-piece set of MS-67 half dollars on Aug. 15 for $11.50; and another two-coin set of MS-67 non-Prooflike half dollars on Sept. 10 for $24.88.

Also, eBay completed sales for red Prooflike 2015-D Lincoln cents include an NGC MS-67 Prooflike red coin that sold Oct. 31 for $34.95; another NGC MS-67 Prooflike red coin that sold Aug. 26 for $15.45; and an NGC MS-68 Prooflike red coin that sold Aug. 30 for $328.33.

The seller of the NGC MS-68 Prooflike red cent, who uses the eBay seller name manorcourtman, indicated to Coin World Nov. 3 that he had found a number of Prooflike coins in the 2015 Uncirculated Mint set after searching through hundreds of the sets.

Another eBay seller was offering an NGC MS-68 Prooflike red 2015-D Lincoln cent with an Early Release label for a Buy It Now price of $699.95.

There were no completed eBay listings for non-Prooflike NGC-graded 2015-D Lincoln cents from the 2015 Uncirculated Mint set.